System Containing Oxygen Enriched Diesel Particulate Filter and Method Thereof

ABSTRACT

A system for treatment of exhaust emissions from a compression-ignited internal combustion engine comprises (A) a superatmospheric-pressurized source of gaseous oxygen, (B) an inlet for the gaseous oxygen of component (A) where the exhaust emissions from the engine flow past the inlet and form a mixture with the gaseous oxygen from the inlet, and (C) a diesel particulate filter or catalyzed diesel particulate filter through which the mixture of engine exhaust emissions and gaseous oxygen flows, where the oxygen content of the mixture is greater than the oxygen content of the exhaust emissions from the engine. A method for improving the performance of a diesel particulate filter or catalyzed diesel particulate filter in a compression-ignited internal combustion engine comprises operating the engine and treating the exhaust emissions from the engine with the exhaust emissions treatment system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional Application No.60/509,720 filed 8 Oct. 2003.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention involves a system comprising a diesel particulatefilter (catalyzed or uncatalyzed) for treatment of exhaust emissionsfrom a compression-ignited internal combustion engine and a method thatis effective for improving the performance of the diesel particulatefilter by operating the engine and treating the engine exhaust emissionswith the system.

2. Description of the Related Art

Future exhaust emission regulations for compression-ignited internalcombustion engines in Europe and North America will require significantreductions of about 50% or more in both particulates and nitrogen oxides(NO_(x)). Diesel particulate filters (DPFs) and in particular catalyzeddiesel particulate filters (CDPFs) are generally effective in removing90% or greater of particulates which are in the form of carbon soot andhydrocarbons. However, there are several areas that could benefit froman improved performance of a DPF or CDPF to include a) compliance withfuture engine exhaust emission regulations, b) the engine operationpractice to reduce NO_(x) formation through exhaust gas recirculationwhich decreases the oxygen concentration in the engine exhaust emissionsavailable for oxidation of particulates, and c) the general buildup ofsoot on a DPF or CDPF which can result in loss of fuel economy andengine wear due to excessive back pressure on the engine as well asmechanical failure of the DPF or CDPF due to an uncontrolled combustionof the soot.

The Derwent WPI abstract of Japanese Publication No. JP 2002/188427Adiscloses a bellows-shaped catalyzed diesel particulate filter whichincludes a power supply terminal for heating a catalyst layer and an airpump for supplying air to a chamber in which the particulate filter isinstalled.

The Derwent WPI abstract of German Publication No. DE 10137050A1discloses treatment of exhaust from an internal combustion engine,especially a diesel engine, that involves a particulate filter which caninclude a supplementary heating unit, a control unit, and a unit forsupplying air to the exhaust where the particulate filter can beregenerated without a reduction in engine power.

Vigeland et al. in U.S. Pat. No. 6,503,296B1 disclose a dense singlephase membrane having both high ionic and electronic conductivity andcapable of separating oxygen from an oxygen containing gaseous mixturewhere the separated oxygen can be used in catalytic and noncatalyticprocesses where oxygen is one of the reactants.

Kakwani et al. in International Publication No. WO 02/14657A1 disclose adiesel engine after treatment exhaust system that uses a combination ofa catalyzed soot filter and a urea selective catalytic reductioncatalyst for simultaneous reduction of particulate matter and NO_(x).

Ellmer et al. in U.S. Pat. No. 6,637,204 disclose a device and methodfor the heating of a catalytic converter for a supercharged internalcombustion engine.

It has now been found that the performance of a diesel particulatefilter (catalyzed or uncatalyzed) can be significantly improved byenriching or increasing the oxygen content of exhaust emissions thatflow through the particulate filter.

SUMMARY OF THE INVENTION

An object of the present invention is to improve the performance of adiesel particulate filter or catalyzed diesel particulate filter in acompression-ignited internal combustion engine.

Another object of the invention is to lower the temperature forregeneration of a diesel particulate filter or catalyzed dieselparticulate filter in a compression-ignited internal combustion engine.

A further object of this invention is to improve exhaust emissionsperformance of a diesel particulate filter or catalyzed dieselparticulate filter in a compression-ignited internal combustion enginefor the reduction of soot, hydrocarbons including polyaromatichydrocarbons, aldehydes and carbon monoxide.

An additional object of the present invention is to improve thedurability of a diesel particulate filter or catalyzed dieselparticulate filter in a compression-ignited internal combustion engine.

Yet an additional object of this invention is to improve the fueleconomy of a compression-ignited internal combustion engine.

Still a further object of the invention is to improve wear performanceof a compression-ignited internal combustion engine.

Additional objects and advantages of the present invention will be setforth in the Detailed Description which follows and, in part, will beobvious from the Detailed Description or may be learned by the practiceof the invention. The objects and advantages of the invention may berealized by means of the instrumentalities and combinations pointed outin the appended claims.

To achieve the foregoing objects in accordance with the presentinvention as described and claimed herein, a system for treatment ofexhaust emissions from a compression-ignited internal combustion enginecomprises (A) a superatmospheric-pressurized source of gaseous oxygen,(B) an inlet for the gaseous oxygen from thesuperatmospheric-pressurized source wherein the exhaust emissions fromthe engine flow past the inlet and form a mixture with the gaseousoxygen from the inlet, and (C) a diesel particulate filter or catalyzeddiesel particulate filter through which the mixture of exhaust emissionsfrom the engine and gaseous oxygen from the inlet flows, wherein theoxygen content of the mixture is greater than the oxygen content of theexhaust emissions from the engine.

In another embodiment of this invention the above described exhaustemissions treatment system comprises one or more additional componentswhich is or are taken from (D) at least one heat source, (E) a controlunit, (F) at least one component selected from the group consisting of adiesel oxidation catalyst, a selective catalytic reduction catalyst anda lean NO_(x) catalyst, and (G) an outlet for recirculating a portion ofthe exhaust emissions from the engine to an air intake of a combustionsystem of the engine.

In a further embodiment of the invention a method for improving theperformance of a diesel particulate filter or catalyzed dieselparticulate filter in a compression-ignited internal combustion enginecomprises operating the engine and treating the exhaust emissions fromthe engine with the above described exhaust emissions treatment systemcomprising components (A), (B) and (C) and optionally one or more of thecomponents (D), (E), (F) and (G).

DETAILED DESCRIPTION OF THE INVENTION

The present invention comprises a system for treatment of exhaustemissions from a compression-ignited internal combustion engine thatcomprises (A) a superatmospheric-pressurized source of gaseous oxygen,(B) an inlet for the gaseous oxygen from thesuperatmospheric-pressurized source wherein the exhaust emissions fromthe engine flow past the inlet and form a mixture with the gaseousoxygen from the inlet, and (C) a diesel particulate filter or catalyzeddiesel particulate filter through which the mixture of exhaust emissionsfrom the engine and gaseous oxygen from the inlet flows, wherein theoxygen content of the mixture is greater than the oxygen content of theexhaust emissions from the engine.

In an embodiment of the invention for the system for treating exhaustemissions as described throughout this application, the gaseous oxygenfrom a superatmospheric-pressurized source or from atmospheric air iscontinuously introduced into the inlet for mixing with the engineexhaust emissions during operation of the compression-ignited internalcombustion engine. In a further embodiment of the invention for thesystem for treating exhaust emissions as described throughout theapplication, the gaseous oxygen from a superatmospheric-pressurizedsource or from atmospheric air is intermittently introduced into theinlet for mixing with the engine exhaust emissions during the operationof the engine which can be based on operating parameters of the engineand/or exhaust system comprising for example exhaust emissionstemperature, diesel particulate filter (catalyzed or uncatalyzed)temperature, engine back pressure, or a combination thereof.

The superatmospheric-pressurized source of gaseous oxygen (A) can be anypressurized source of oxygen that can be introduced into the exhaustsystem of a compression-ignited internal combustion engine and that uponmixing with exhaust emissions from the engine forms a mixture having anoxygen content greater than the oxygen content of the exhaust emissionsfrom the engine. The source of gaseous oxygen can be air, oxygen, anoxygen containing gas, or a mixture thereof. The oxygen containing gascan have an oxygen content of 1 to 99% by volume, and in other instancescan have an oxygen content greater than 21% by volume to 99% by volume,greater than 21% by volume to 70% by volume, and greater than 21% byvolume to 40% by volume. The source of gaseous oxygen will generallyhave a pressure greater than the atmospheric pressure, and in otherinstances will have a pressure that is 1.05 to 1000 times theatmospheric pressure or 1.1 to 500 times the atmospheric pressure. Inanother embodiment of the invention the source of the gaseous oxygen canhave a pressure greater than the exhaust pressure of the exhaust system,and in several instances the source of the gaseous oxygen can have apressure that is 1.05 to 1000 times or 1.1 to 500 times the exhaustpressure of the exhaust system. The source of gaseous oxygen can raisethe oxygen content of the mixture, that forms from exhaust emissionsfrom the engine and the source of gaseous oxygen, to be greater than theoxygen content of the exhaust emissions from the engine by at least 0.1%by volume, and in other instances by at least 1% by volume, by at least2% by volume, by at least 3% by volume, by at least 4% by volume, by atleast 5% by volume, by at least 6% by volume and by at least 7% byvolume. In another embodiment of the invention the oxygen content of themixture from the engine exhaust emissions and the source of gaseousoxygen can be 10.1 to 99% by volume, and in other embodiments can be 11to 50% by volume, and 12 to 30% by volume. Thesuperatmospheric-pressurized source of gaseous oxygen can comprise acompressor, a blower, a compressed gas storage container, or a mixturethereof. The gas in the compressed gas storage container can be air,oxygen, or an oxygen containing gas having an oxygen content asdescribed hereinabove. In an embodiment of the invention the source ofgaseous oxygen can be obtained from a compressor or blower that isnormally present such as for example a turbocharger, a supercharger, anda compressor for air brakes. In another embodiment of this invention thesource of gaseous oxygen can be obtained from a dedicated compressor orblower which can be powered by an electric motor, the internalcombustion engine, the exhaust flow of the engine, or a mixture thereof.In a further embodiment of the present invention the source of gaseousoxygen can be obtained from a combination of a compressor or blowernormally present and a dedicated compressor or blower. The compressorsand/or blowers of this invention can compress or blow air and in certaininstances oxygen or an oxygen containing gas having an oxygen content asdescribed hereinabove.

The source of gaseous oxygen can further comprise, in addition to acompressor, a blower, a compressed gas storage container, or a mixturethereof, a permeable membrane wherein the membrane provides oxygen or agas having an increased oxygen content from mixture of gases thatincludes oxygen. Generally the mixture of gases that includes oxygen,from which the permeable membrane provides oxygen or a gas having anincreased oxygen content, is air. In an embodiment of the invention thepermeable membrane is an organic polymeric permeable membrane, asdescribed in U.S. Pat. No. 4,537,606, having a higher permeability foroxygen relative to nitrogen. Organic polymers which can function aspermeable membranes include for example poly(butadiene), ethylcellulose, poly(propylene), poly(styrene), poly(dimethylsiloxane) andpolysulfone. Permeable membranes from organic polymers are availablecommercially and include an oxygen enriching membrane Prism® PA4050 fromAir Products. In another embodiment of this invention the permeablemembrane is a dense single phase permeable membrane fromlanthanide-transition metal oxide material having both high ionic andelectronic conductivity and capable of separating oxygen from a mixtureof gases that includes oxygen as described in U.S. Pat. No. 6,503,296.In an embodiment of the invention a blower or compressor drives airthrough an organic polymeric permeable membrane, and the oxygen enrichedgas exiting the permeable membrane is stored in a compressed gas storagecontainer for later use and/or is allowed to enter the engine exhaustsystem. In another embodiment of the invention a dense single phasepermeable membrane produces oxygen from air, the produced oxygen iscompressed with a compressor or blower, and the compressed oxygen isstored in a compressed gas storage container for future use and/orallowed to enter the engine exhaust system.

The system of the present invention for treating exhaust emissions froma compression-ignited internal combustion engine can comprise (B) aninlet for the gaseous oxygen of component (A) where the inlet isgenerally downstream from the entrance of the engine exhaust emissionsinto the exhaust system and generally upstream from a DPF or CDPF. Theinlet of component (B) can include a valve for controlling the flow andflow rate of the gaseous oxygen of component (A) into the exhaustsystem.

The system of the present invention for treating the exhaust emissionsfrom a compression-ignited internal combustion engine can comprise (C) adiesel particulate filter (DPF) or a catalyzed diesel particulate filter(CDPF). In an embodiment of the invention the treatment system forengine exhaust emissions comprises a CDPF. The DPF or CDPF can includefilters from a porous ceramic wall-flow monolith, a wire mesh, wound orpacked ceramic fiber media, an open-cell ceramic foam and a sinteredmetal. In an embodiment of the invention the DPF or CDPF is from aporous wall-flow ceramic monolith. The porous wall-flow ceramic monolithcan be composed of one or more ceramic materials such as for examplecordierite, spodumene, zirconium silicate, alumina, silica, zirconia,silicon carbide, silicon nitride, mullite, and alumina-silica-magnesia.The CDPF can be prepared by coating a filter substrate, such as a porouswall-flow ceramic monolith from cordierite, with a catalyst which isgenerally a metal or metal oxide where the metal can be platinum,palladium, rhodium, ruthenium, vanadium, magnesium, calcium, strontium,barium, copper, silver, or a mixture thereof. The catalyst typicallyincludes platinum due to its high catalytic activity which substantiallylowers the temperature for regeneration of the CDPF from trapped carbonsoot. The preparation of a CDPF, as described in InternationalPublication No. WO 02/14657, generally involves impregnating the filtersubstrate with a solution or slurry, which is usually water based, of acatalyst precursor followed by drying and calcining to leave a metal ormetal oxide catalyst. The preparation of a CDPF can also includeapplication of an oxide catalyst carrier, such as alumina or silica orzirconia, to the filter substrate prior to application of the catalystto enhance catalyst surface activity and durability. A CDPF can alsocontain a promoter to include an alkaline earth metal oxide such asmagnesium oxide or a rare earth metal oxide such as cerium dioxide. Thecatalyst coating on the filter substrate, such as a wall-flow ceramicmonolith, can comprise 5 to 150 g/ft³ of a catalyst metal, and in otherinstances can comprise 15 to 100, 25 to 60, or 40 to 85 g/ft³ of acatalyst metal. Catalyzed diesel particulate filters are availablecommercially from various suppliers including Engelhard Corporation.

In an embodiment of the invention the DPF or CDPF of component (C) cancomprise two or more sections where the sections can run from theentrance to the exit of the filter and where each section is capable ofbeing separately regenerated while the other section or sectionscontinue to filter engine exhaust emissions. The sections can beseparated from each other by some means to include a semipermeablebarrier such as ceramic glass beads or by an impermeable barrier such asa nonporous ceramic or metal. The sectioned filter can have a means suchas a baffle for directing a flow of the gaseous oxygen from component(A) to a section of the filter for regeneration and for directing a flowof engine exhaust emissions to the other section or sections of thefilter. The means for directing a flow of the gaseous oxygen ofcomponent (A) and the engine exhaust emissions will generally bechangeable so that each section of the filter can be regenerated under aflow of the gaseous oxygen from component (A). In another embodiment ofthis invention the DPF or CDPF can comprise two or more separate unitsthat are parallel and in close proximity to each other. A means such asa manifold can selectively deliver gaseous oxygen of component (A) toone of the units of the filter for regeneration while another means suchas a second manifold can selectively deliver engine exhaust emissions tothe other unit or units of the filter.

In an embodiment of the invention as described throughout thisapplication, the system for treatment of exhaust emissions from acompression-ignited internal combustion engine comprises atmospheric airas a source of gaseous oxygen, an inlet for the atmospheric air whereinexhaust emissions from the engine flow through a venturi which draws inthe atmospheric air through the inlet forming a mixture of exhaustemissions and atmospheric air, and a diesel particulate filter orcatalyzed diesel particulate filter through which the mixture of exhaustemissions and atmospheric air flows wherein the oxygen content of themixture is greater than the oxygen content of the exhaust emissions fromthe engine.

The system of the present invention as described above for treatingexhaust emissions from a compression-ignited internal combustion enginecan further comprise one or more additional components taken from (D) atleast one heat source, (E) a control unit, (F) at least one componentselected from the group consisting of a diesel oxidation catalyst, aselective catalytic reduction catalyst and a lean NO_(x) catalyst, and(G) an outlet for recirculating a portion of the exhaust emissions fromthe engine to an air intake of a combustion system of the engine. Theone or more additional components (D), (E), (F) and (G) can be presentto further improve the performance of the exhaust emissions treatmentsystem.

The heat source of component (D) can be any source of heat to include aheater, a heat exchanger, and/or the injection and combustion of fuel inthe exhaust system. One or more heat sources can be present to heat theexhaust emissions from the engine, to heat the gaseous oxygen ofcomponent (A), to heat a DPF or CDPF of component (C), to heat the oneor more catalysts of component (F), or a combination thereof. The heaterof component (D) is usually an electrical heater to include for examplea heating filament. The heat exchanger of component (D) can obtainsurplus heat from any heat source of the engine and/or related systemscomprising for example heat from the engine, heat from the engineexhaust emissions, heat from various air conditioners and/or coolers,heat from an air brake system, heat from the DPF or CDPF outletemissions, or a combination thereof.

The control unit of component (E) is usually an electronic control unitand can be a computer such as for example the engine's electroniccommand module. The control unit (E) can control the components (A),(B), (C), (D), (F), (G) and/or their related subcomponents as describedthroughout this disclosure based on sensors which are generally locatedthroughout the exhaust system and which can measure temperature,pressure and composition of the exhaust system gases. The control unitgenerally functions to optimize the performance of the exhaust treatmentsystem.

Component (F) of the present invention can comprise at least onecatalyst selected from a diesel oxidation catalyst (DOC), a selectivecatalytic reduction (SCR) catalyst, and a lean NO_(x) catalyst. In anembodiment of the invention the exhaust treatment system includes a DOC.In another embodiment of the present invention the exhaust treatmentsystem includes a SCR catalyst or a lean NO_(x) catalyst. In stillanother embodiment of this invention the exhaust treatment systemincludes a DOC and either a SCR catalyst or a lean NO_(x) catalyst.

A DOC when present in the exhaust treatment system can be locatedanywhere in the system which will improve performance, but is generallylocated either upstream from components (B) and (C) or downstream of aSCR catalyst or lean NO_(x) catalyst. A DOC can oxidize variouscomponents in the exhaust emissions from the engine including carbonmonoxide and hydrocarbons as well as any surplus reductants such asammonia or hydrocarbons from a SCR catalyst or lean NO_(x) catalyst asdescribed below. A DOC is generally a catalyzed ceramic or metallicmonolith that is sufficiently large in size, in terms of volume capacityand cell size, so that it does not readily become clogged with carbonsoot. A DOC can be prepared by applying to a monolith substrate awashcoat layer which can include alumina with a zeolite or a rare earthmetal or an alkaline earth metal followed by application of a catalystwhere the metal of the catalyst can be platinum, palladium or a mixturethereof. Diesel oxidation catalysts are available commercially fromseveral suppliers.

A SCR or lean NO_(x) catalyst when present in the exhaust treatmentsystem will generally be located downstream of the DPF or CDPF ofcomponent (C). Both a SCR or a lean NO_(x) catalyst can reduce NO_(x)from the engine exhaust emissions to nitrogen using a reductant that isrespectively ammonia, or an ammonia precursor of aqueous urea, orhydrocarbons from the fuel. The reductant can be introduced into theexhaust system from a valved inlet upstream of the SCR or lean NO_(x)catalyst. A SCR catalyst, as described in International Publication No.WO 02/14657, can include a flow-through monolith to which is applied acatalyst and a transition metal oxide binder where the catalyst can bean iron or copper or titanium/vanadium exchanged zeolite. A lean NO %catalyst, as described in International Publication No. WO 02/14657, canbe of the low or high temperature type. The low temperature type isplatinum based that can use a platinum/zeolite or platinum/aluminacatalyst. The high temperature type uses a base metal/zeolite catalystsuch as copper/zeolite. Both SCR and lean NO_(x) catalysts arecommercially available with SCR catalysts being supplied by EngelhardCorporation.

Component (G) of the present invention can comprise an outlet forexhaust gas recirculation which can be located throughout the exhausttreatment system, but it is generally located just downstream from theentrance of the exhaust emissions from the engine into the exhausttreatment system. The outlet of component (G) can include a valve forcontrolling the flow and flow rate of exhaust emissions back to an airintake of the combustion system of the engine.

A method of the present invention for improving the performance of adiesel particulate filter or catalyzed diesel particulate filter in acompression-ignited internal combustion engine comprises operating theengine and treating the exhaust emissions from the engine with theexhaust emission treatment system as described throughout thisdisclosure comprising components (A), (B) and (C) and optionally one ormore of the components (D), (E), (F) and (G). As indicated above in theSummary of the Invention section the exhaust emissions treatment systemand method of the present invention for using the system in theoperation of a compression-ignited internal combustion engine improvesthe performance of a DPF or CDPF which can result in a lower temperaturefor regeneration of the DPF or CDPF, a general improvement in exhaustemissions performance in terms of soot and hydrocarbons and carbonmonoxide, improved durability of the DPF or CDPF, improved fuel economy,and improved engine wear performance. In an embodiment the system andmethod of the present invention improve the performance of a DPF or CDPFin a compression-ignited internal combustion engine that employs exhaustgas recirculation to help control NO_(x) generation. While exhaust gasrecirculation can reduce NO_(x) generation, it can adversely affect theperformance of a DPF or CDPF since it decreases the oxygen content ofthe exhaust emissions from the engine which is available for oxidationof soot. In another embodiment of the method of the present inventionthe temperature for regeneration of the DPF or CDPF is decreased by 1 to200° C., and in other embodiments is decreased by 5 to 150° C., and by10 to 100° C. In a further embodiment of the method of the invention therate for regeneration of the DPF or CDPF is increased.

Catalyzed Diesel Particulate Filter Evaluations

A diesel engine was operated on a dynamometer in a series of CDPFevaluations that included three base line runs and two runs in whichcompressed air was used to increase the oxygen content of the gasespassing through the CDPF. Measurements included the gas temperature nearthe entrance of the CDPF, pressure in the exhaust system, and oxygencontent in the exhaust system upstream of the CDPF. Regenerationoccurred based on the maximum pressure drops obtained for the base lineruns at 357° C. and 9.2% by volume oxygen and for the compressed airruns at 289° C. and 15.7% by volume oxygen.

Each of the documents referred to in this Detailed Description of theInvention section is incorporated herein by reference. All numericalquantities in this application used to describe or claim the presentinvention are understood to be modified by the word “about” except whereexplicitly indicated otherwise. All chemical treatments or contentsthroughout this application regarding the present invention areunderstood to be as actives unless indicated otherwise even thoughsolvents or diluents may be present.

1. A system for treatment of exhaust emissions from acompression-ignited internal combustion engine, comprising: (A) asuperatmospheric-pressurized source of gaseous oxygen; (B) an inlet forthe gaseous oxygen from the superatmospheric-pressurized source whereinthe exhaust emissions from the engine flow past the inlet and form amixture with the gaseous oxygen from the inlet; and (C) a dieselparticulate filter or catalyzed diesel particulate filter through whichthe mixture of exhaust emissions from the engine and gaseous oxygen fromthe inlet flows, wherein the oxygen content of the mixture is greaterthan the oxygen content of the exhaust emissions from the engine.
 2. Thesystem of claim 1 wherein the gaseous oxygen is continuously introducedinto the inlet for mixing with the engine exhaust emissions during theoperation of the engine.
 3. The system of claim 1 wherein the gaseousoxygen is intermittently introduced into the inlet for mixing with theengine exhaust emissions during the operation of the engine.
 4. Thesystem of claim 1 wherein the oxygen content of the mixture is greaterthan the oxygen content of the exhaust emissions from the engine by atleast 0.1% by volume.
 5. The system of claim 1 wherein the source ofgaseous oxygen is air, oxygen, an oxygen containing gas, or a mixturethereof wherein the oxygen containing gas has an oxygen content of 1 to99% by volume.
 6. The system of claim 1 wherein thesuperatmospheric-pressurized source of gaseous oxygen comprises acompressor, a blower, a compressed gas storage container, or a mixturethereof.
 7. The system of claim 6 wherein the gas in the compressed gasstorage container is air, oxygen, or an oxygen containing gas having anoxygen content greater than 21% by volume to 99% by volume.
 8. Thesystem of claim 6 wherein the superatmospheric-pressurized source ofgaseous oxygen further comprises a permeable membrane wherein themembrane provides oxygen or a gas having an increased oxygen contentfrom a mixture of gases that includes oxygen.
 9. The system of claim 1wherein the diesel particulate filter or catalyzed diesel particulatefilter comprises 2 or more sections wherein each section is capable ofbeing separately regenerated.
 10. The system of claim 1 wherein thecatalyzed diesel particulate filter is a coated wall-flow ceramicmonolith wherein the coating comprises 5 to 150 g/ft³ of a catalystmetal.
 11. The system of claim 10 wherein the catalyst metal isplatinum, palladium, rhodium, ruthenium, vanadium, magnesium, calcium,strontium, barium, copper, silver, or a mixture thereof.
 12. A systemfor treatment of exhaust emissions from a compression-ignited internalcombustion engine, comprising: atmospheric air as a source of gaseousoxygen; an inlet for the atmospheric air wherein exhaust emissions fromthe engine flow through a venturi which draws in the atmospheric airthrough the inlet forming a mixture of exhaust emissions and atmosphericair; and the diesel particulate filter or catalyzed diesel particulatefilter of claim 1 through which the mixture of exhaust emissions andatmospheric air flows wherein the oxygen content of the mixture isgreater than the oxygen content of the exhaust emissions from theengine.
 13. The system of claim 1, further comprising: (D) at least oneheat source.
 14. The system of claim 13 wherein the heat source is aheater or a heat exchanger.
 15. The system of claim 1, furthercomprising: (E) a control unit.
 16. The system of claim 1, furthercomprising: (F) at least one component selected from the groupconsisting of a diesel oxidation catalyst, a selective catalyticreduction catalyst and a lean NO_(x) catalyst.
 17. The system of claim1, further comprising: (G) an outlet for recirculating a portion of theexhaust emissions from the engine to an air intake of a combustionsystem of the engine.
 18. A method for improving the performance of adiesel particulate filter or catalyzed diesel particulate filter in acompression-ignited internal combustion engine, comprising: operatingthe engine; and treating the exhaust emissions from the engine with thesystem of claim
 1. 19. The method of claim 18 wherein the temperaturefor regeneration of the diesel particulate filter or catalyzed dieselparticulate filter is decreased by 1 to 200° C.
 20. The method of claim18 wherein the rate for regeneration of the diesel particulate filter orcatalyzed diesel particulate filter is increased.